Vibration motor holding structure and vibration motor

ABSTRACT

There is provided a holding structure to hold a vibration motor on a circuit board with a sufficient holding strength using an inexpensive and simple means such as caulking and bonding and a vibration motor held on a circuit board using the holding structure. The holding structure having a holder clamps a vibration motor body having an eccentric weight at an end of the rotation shaft around the outer periphery from the outside and supports the vibration motor at the lower part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/151,354, filed May 6, 2008, which claims priority to Japanese PatentApplication No. 2007-124572, filed May 9, 2007, and Japanese PatentApplication No. 2007-137988, filed May 24, 2007, all of which areexpressly incorporated herein by reference and made a part hereof.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

TECHNICAL FIELD

The present invention relates to a holding structure for vibrationmotors installed in portable communication devices such as mobile phonesand PHSs and game machines to generate body sensory vibration and avibration motor provided with the holding structure.

BACKGROUND OF THE INVENTION

Portable communication devices inform the wearer of an incoming call byring tones or body sensory vibration generated by the rotation of aneccentric weight of a built-in vibration motor. The modes are switchedas necessary. Some of game machines let the operator sense vibrationgenerated by the vibration motor in the machine in the course of gamesfor more fun.

Such kind of vibration motor is secured to a circuit board in thedevice/machine and generates and transmits vibration to thedevice/machine housing, whereby the wearer/operator of the communicationdevice/game machine senses the vibration. Such an example is describedin Japanese Patent Application Laid-open No. 2005-312282, wherein abuilt-in vibration motor is mounted on a circuit board in such asuspended manner that a motor case is clamped by a mountain frameradially from the outside around the upper half of the motor case andfolded legs at the bottom of the mounting frame are bonded along theedges of a cutout formed in the circuit board.

In another example described in Japanese Patent Application Laid-openNo. H11-234943, a vibration motor is mounted on a circuit board in sucha manner that a cylindrical motor body is retained by a metal holderframe, an eccentric weight is fixed to one end of a motor shaft, creamedsolder applied to the circuit board is melted in a heating furnace tosecure the entire structure of the motor to the circuit board.

The above mounting methods do not ensure that the vibration motor isheld by the mounting frame securely enough for the motor vibrationgenerated by the rotation of the eccentric weight or for accidental dropof the device. Therefore, some countermeasures are provided such as spotwelding between the mounting frame and motor case.

However, spot welding requires an expensive spot welding apparatus andproduces spot residue or flash, which has to be removed. When theresidue or flash remains, it may adversely affect the circuitryoperation or motor rotation. Particularly, if the motor case is deformedby spot welding, it may cause a problem with the motor rotation.

On the other hand, there is an increasing demand for downsizing,flattening, and light-weight in recent portable communication devicesand game machines. The vibration motors for generating body sensoryvibration are not exceptional among many circuit parts and functionalparts mounted in a limited space in the device. They are also requiredto be smaller. However, their downsizing has a limitation since theyhave to generate the necessary vibration.

It has therefore been desired to generate vibration having a large bodysensory effect using the same vibration motor.

SUMMARY OF THE INVENTION

The present invention has been made in light of the above problem and itis an object of the present invention to provide a vibration motorholding structure comprising a holder providing sufficient holdingstrength using an inexpensive and simple method such as caulking andbonding without installing expensive equipment such as a spot weldingapparatus and a vibration motor held on a circuit board using theholding structure.

It is another object of the present invention to provide a vibrationmotor holding structure generating vibration having a large body sensoryeffect and a vibration motor having the holding structure.

In order to achieve the above object, according to a first aspect of thepresent invention, the holder clamps a vibration motor having aneccentric weight at an end of a rotation shaft around the outerperiphery from the outside and supports the vibration motor at the lowerpart.

The holder of the present invention is preferably formed by pressing asheet of steel plate and further folding predetermined parts atpredetermined positions into a shape to clamp the motor around the outerperiphery from the outside and support the motor at the lower part.

The holder of the present invention preferably has wing-like legsextending outward in parallel to the motor shaft at the radially outeredges of the vibration motor.

A vibration motor using the holding structure comprising the holderhaving the above wing-like legs is secured on a circuit board with thewing-like legs fixed at the side edges of a cutout of the circuit boardby reflow soldering.

According to a second aspect of the present invention, a tilting meansfor mounting the vibration motor on a circuit board in a tilted mannerin the longitudinal direction of the rotation axis is provided to thevibration motor holding structure or to the circuit board.

In the above structure, the tilting means is comprised of at least onepair of wing-like legs provided to the holder as the vibration motorholding structure, the wing-like legs tilting in relation to the axisline of the vibration motor and extending outward at the radially outeredges of the vibration motor being fixed at the side edges of a cutoutof the circuit board to hold the vibration motor on the circuit board.

It is preferable that the wing-like legs are formed by pressing a steelplate and folding predetermined parts it at predetermined positions.

A vibration motor using the holding structure comprising the holderhaving the above wing-like legs is secured on a circuit board with thewing-like legs fixed at the side edges of a cutout of the circuit boardby reflow soldering.

In the present invention, a vibration motor having an eccentric weightat an end of the rotation shaft is clamped around the outer peripheryfrom the outside and further supported at the lower part, securelyholding the entire vibration motor. Therefore, the vibration motor isnot inconveniently removed from the circuit board while the motorgenerates vibration or when the portable communication device isaccidentally dropped, preventing the circuitry operation or function ofthe portable communication device from being disabled.

A vibration motor body is secured and held on the holder by a simple andinexpensive means such as caulking and bonding without expensiveequipment or means such as spot welding.

A holder for holding the vibration motor body on a circuit board caneasily be formed by pressing and folding a sheet of steel plate,realizing low manufacturing cost.

Furthermore, in the present invention, the vibration motor is mounted ona circuit board in a tilted manner in the axial direction to increasethe magnitude of vibration in the vibration motor shaft direction. Ahigh level of body sensory vibration can be obtained using a vibrationmotor of the same standard under the same condition. Consequently, avibration motor generating a necessary level of body sensory vibrationcan be downsized, which is advantageous in providing portablecommunication devices and reducing machine size, weight, and thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object and other advantages of the present invention willbecome more apparent by describing in detail the preferred embodiment ofthe present invention with reference to the attached drawings, in which:

FIG. 1 is a perspective view for explaining how a vibrating motor ismounted on a circuit board using a holder as a holding structure of thepresent invention;

FIG. 2 is a perspective view showing a vibration motor mounted on acircuit board according to an embodiment of the present invention;

FIG. 3 is a plan view of a holder material from which the holdingstructure shown in FIG. 2 is manufactured;

FIG. 4 is a perspective view of an embodiment of the holder of thepresent invention;

FIG. 5 is an illustration showing a vibration motor mounted on a circuitboard according to another embodiment of the present invention;

FIG. 6 is also an illustration showing a vibration motor mounted on acircuit board according to a further embodiment of the presentinvention;

FIG. 7 is a perspective view of a holder as the holding structure shownin FIG. 6;

FIG. 8 is an illustration explaining how a holder is mounted in a tiltedmanner;

FIG. 9 is a plan view of a holder material from which the holder shownin FIG. 7 is manufactured;

FIG. 10 is a schematic view of an apparatus for measuring the magnitudeof vibration generated by the vibration motor of the present invention;

FIG. 11 is a perspective view explaining the direction of vibrationgenerated by the vibration motor of the present invention;

FIG. 12 is a perspective view showing a vibration motor mounted on acircuit board according to a further embodiment of the presentinvention.

DETAILED DESCRIPTION

The present invention will now be described hereafter with reference tothe drawings.

FIG. 1 is an exploded perspective view of a structure to hold on acircuit board a vibration motor used for generating vibration in aportable communication device.

FIG. 1 shows a vibration motor body 1 covered with a cylindrical motorframe, an eccentric weight 10 to be fixed to a rotation shaft 11 of thevibration motor body 1 for generating vibration, and a holder 2 designedto clamp the vibration motor body 1 around its outer periphery. Entirelyclamped by the holder 2 from the outside with the eccentric weight 10fixed thereto, the vibration motor body 1 is inserted in a cutout 31 ofa circuit board 3. A resin bracket 12 is attached to the vibration motorbody 1 at its rear end (the top right in the figure). A conductiveexternal terminal 13 is fixed to the bracket 12. Brush fixed terminalsof the vibration motor body 1 are electrically connected to the externalterminal 13.

FIG. 2 shows the vibration motor body 1 mounted on the circuit board 3using the holder 2 of the present invention.

The holder 2 is formed by pressing a steel plate (such as a rolledcarbon steel plate SPCC) having a thickness of 0.1 mm to 0.3 mm andplated for a good affinity to solder into a shape shown in FIG. 3, whichis folded by a folding machine (not shown) to create a three-dimensionalshape shown in FIG. 4. The holder 2 has an inner diameter slightlysmaller than the outer diameter of the motor frame of the vibrationmotor body 1. Holder materials having tin-based plating are advantageousin cost. However, gold-plating is preferable where soldering propertyhas a priority. When the holder material is nickel silver, no plating isrequired because it has a good affinity to solder.

After the holder material shown in FIG. 3 is folded by a folding machineinto a shape shown in FIG. 4, an upper edge A and a lower edge B of thematerial closely face each other, one projection F of the material formsa vertical piece 21 of the holder 2, and the other small projection Eforms an upright piece 22 of the holder 2. The vertical piece 21 andupright piece 22 serve as stoppers for the vibration motor body 1 whenit is inserted in the holder 2. Cut patterns C and D of the holdermaterial form wing-like legs 23 a, 23 b and 24 a, 24 b of the holder 2after folded. Opening G forms an opening 25 of the holder 2. Parts H andJ of the material form straps 25 a, 25 b, and 26 b. The end positions ofthe cut patterns C and D can be changed to alter the height of thewing-like legs 23 a, 23 b, 24 a, and 24 b of the holder 2, whereby themounting position of the vibration motor body 1 on the circuit board 3can be adjusted. The opening 25 is used for adjustment in folding butmay be eliminated.

Mounting of the vibration motor on a circuit board according to thepresent invention will be described hereafter with reference to FIG. 1.

The assembled vibration motor body 1 is inserted in the holder 2 shownin FIG. 4 from its one end (the rear end in FIG. 4) until the front endof the vibration motor body 1 makes contact with the vertical piece 21and the upright piece 22. When getting close contact with each other,the entire holder 2 is caulked using a caulking machine (not shown).Then, the eccentric weight 10 is caulked to the rotation shaft 11protruding from the front end of the holder 2. As a result of caulking,the upper edge A and the lower edge B of the holder 2 are in closecontact with each other and serve as a resilient clamping piece, wherebythe vibration motor body 1 and the holder 2 are locked together to forma vibration motor unit. In this case, the locking of the holder 2 to thevibration motor body 1 is enhanced by applying an adhesive to the innersurface of the holder 2 entirely or partially.

The upper edge A and the lower edge B of the holder 2 are designed to beslightly separated immediately after being processed, but make closecontact with each other when the holder 2 is caulked after the vibrationmotor body 1 is inserted, holding the vibration motor body 1 in a morereliable manner with increased holding strength.

On the other hand, the circuit board 3 on which circuit wirings arepreviously printed is prepared and creamed solder layers 3 a, 3 b, 3 c,and 3 d are applied at predetermined positions along the side edges of acutout 31 formed at a predetermined position of the circuit board 3 (seeFIG. 1).

The vibration motor unit prepared as described above is inserted in thecutout 31 of the circuit board 3 with the rotation shaft 11 parallel tothe circuit board 3 and secured on the circuit board 3. At the time, thevibration motor unit is positioned on the circuit board 3 so that thewing-like legs 23 a and 23 b are placed on the solder layer 3 a, thewing-like legs 24 a and 24 b are placed on the solder layer 3 c, and thehorizontal legs 13 a and 13 a of the external terminal 13 at the end ofthe vibration motor body 1 are placed on the creamed solder layers 3 band 3 d.

The vibration motor unit supported by the wing-like legs 23 a, 23 b, 24a, and 24 b on the circuit board 3 is transferred together with thecircuit board 3 into a reflow furnace (not shown) where the vibrationmotor unit is heated at stepwise elevated temperatures, causing thecreamed solder layers to melt. Leaving the reflow furnace, the vibrationmotor unit is secured to the circuit board 3.

In this way, the vibration motor having the eccentric weight 10 ismounted on the circuit board 3.

FIG. 5 shows a vibration motor with two eccentric weights of the presetinvention.

The relationship between the vibration motor body 1 and the holder 2 inthis embodiment is the same as in the embodiment having a singleeccentric weight shown in FIG. 2 and an explanation thereof is omitted.The same components as in FIG. 2 are referred to by the same referencenumerals. In this embodiment, two eccentric weights 10 a and 10 b areused.

The vibration motor having two eccentric weights realizes a high levelof the magnitude of vibration even if the vibration motor is small,allowing the mounting board to have a reduced thickness and contributingto reduction in the thickness of communication devices.

In the above embodiments, the vibration motor body 1 has a cylindricalouter motor frame, but the outer motor frame may be rectangular. Thenumber of the wing-like legs 23 a, 23 b, 24 a, and 24 b and straps 25 a,25 b, and 26 a provided to the holder may be changed depending on howthe holder material is pressed.

Further embodiments of the vibration motor holding structure of thepresent invention will be described hereafter.

FIG. 6 is a perspective view of a vibration motor having an embodimentof the holding structure of the present invention and mounted on acircuit board.

The vibration motor body 1 and the metal holder clamping the vibrationmotor 1 around the outer periphery have nearly the same structures asshown in FIGS. 1 to 4 and, therefore, the same components are notexplained here and referred to by the same reference numerals in aholder of FIG. 7.

In this embodiment, a holder 2′ is partly different from the holder 2shown in FIG. 4. As shown in FIG. 8, a plane including the wing-likelegs 24 a and 24 b is tilted in relation to the longitudinal axis line kof the holder 2′ by an angle θ so that the holder 2′ dives in the frontend (the left in the figure).

The holder 2′ is formed by pressing a steel plate (such as a rolledcarbon steel plate SPCC) having a thickness of 0.1 mm to 0.3 mm andplated for a good affinity to solder into a shape shown in FIG. 9, whichis folded by a folding machine (not shown) to create a three-dimensionalshape shown in FIG. 7.

Center part B of the holder material forms a top flat part 2 a of theholder 2′ (see FIG. 7). Lateral parts C1 and C2 form wing-like legs 23 aand 24 a, respectively and lateral parts D1 and D2 form wing-like legs23 b and 24 b, respectively. Protrusions E and F are bent to formretention pieces 21 and 22, respectively.

Holder materials having tin-based plating are advantageous in terms ofcost. However, gold-plating is preferable where soldering property has apriority. When the holder material is nickel silver, no plating isrequired because it has a good affinity to solder.

Referring back to FIG. 6, the circuit board 3 is a printed circuit (notshown). The cutout 31 is formed at a position where no wiring for theprinted circuit is provided to accept the vibration motor unit. Creamedsolder layers 3 a, 3 c, and 3 d are applied at predetermined positionsalong the side edges of the cutout 31. The position of the creamedsolder layer 3 a corresponds to the positions of the wing-like legs 23 aand 23 b of the holder 2′. The position of the creamed solder layer 3 ccorresponds to the positions of the wing-like legs 24 a and 24 b of theholder 2′. The position of the creamed solder layer 3 d corresponds tothe position of an external terminal 13 at the rear end of the vibrationmotor body 1.

Mounting of the vibration motor unit on the circuit board will bedescribed hereafter.

Referring to FIG. 7, the cylindrical vibration motor body 1 is insertedin the holder 2′ previously folded into the three-dimensional shape fromthe back on the right until the front end of the vibration motor body 1makes close contact with the retention pieces 21 and 22 at the front endof the holder 2′. When getting close contact with each other, the holder2′ is caulked. If the holder 2′ has an inner diameter slightly smallerthan the outer diameter of the motor frame of the vibration motor body1, the holder 2′ can provides a resilient clamping force. The holder 2′may be locked to the vibration motor body 1 by some means other thancaulking such as bonding and welding. Then, an eccentric weight 10 ispress-fitted on the rotation shaft protruding from the front end of theholder 2′.

The vibration motor unit prepared as described above is inserted in thecutout 31 of the circuit board 3 on which circuits are pre-printed andpositioned on the circuit board 3 so that the wing-like legs 23 a and 23b of the holder 2′ are placed on the creamed solder layer 3 a, thewing-like legs 24 a and 24 b, on the creamed solder layer 3 c and theexternal terminal 13, on the creamed solder layer 3 d. Consequently, thevibration motor unit is tilted with the front end (the eccentric weightend) down.

The vibration motor unit thus placed on the circuit board 3 with thefront end down as shown in FIG. 6 is conveyer-transferred into a reflowfurnace (not shown) where the vibration motor unit is heated at stepwiseelevated temperatures, causing the creamed solder layers 3 a, 3 c, and 3d to melt. Leaving the reflow furnace, the circuit board is cooled downand the vibration motor unit is securely mounted on the circuit board 3.

The following experiments were conducted to measure the magnitude ofvibration of the vibration motor mounted on a circuit board in a tiltedmanner.

As shown in FIG. 10, a hard resin block 100 of approximately 100 g(corresponding to the average weight of a portable cellular phone) ispartly cut out to form an opening 100 a. A vibration motor unit isimmobilized on the resin block 100 with an eccentric weight 10 acceptedin the opening 100 a. The magnitude of vibration generated by thevibration motor was measured at five positions A, B, C, D, and E shownin FIG. 10 using a uniaxial vibration detectable acceleration sensor. InExperiment 1, the vibration motor unit was immobilized with the rotationshaft parallel to the plane of the resin block 100 (prior art). InExperiment 2, the vibration motor unit was immobilized on the resinblock 100 in a tilted manner with the eccentric weight end down (thepresent invention). The tilting angle of the vibration motor unit inExperiment 2 was 15 degrees. The following results were obtained.

Positions A B C D E Experiment 1 0.808 0.606 0.559 0.086 0.063Experiment 2 0.672 0.559 0.552 0.181 0.152 (unit: N (newton))

The above results reveal that the magnitude of vibration is more thantwo times larger at the positions D and E when the vibration motor istilted compared with the prior art of no-tilting manner. In other words,in FIG. 11, the magnitudes of vibration in the directions X and Y arenearly unchanged; however, the magnitude of vibration in the direction Zof the present invention is significantly increased. Consequently, whenthe vibration motor is installed in a device, the device provides a muchhigher level of body sensory vibration than the prior one.

FIG. 12 shows an embodiment in which the holding structure of thepresent invention is applied to a vibration motor with two eccentricweights.

In this embodiment, eccentric weights 10 a and 10 b are attached to thevibration motor body 1 at both ends of the rotation shaft and thevibration motor body 1 is mounted on the circuit board 3 in a tiltedmanner with the eccentric weight 10 a end down. The other configurationis the same as in the embodiment shown in FIG. 6 and the same componentsare referred to by the same reference numerals.

Experiments showed that the magnitude of vibration in the direction Z orin the longitudinal direction of the rotation shaft of the vibrationmotor is increased also in this embodiment. Furthermore, a vibrationmotor with two eccentric weights generates a large magnitude ofvibration at any position and particularly in the direction Z than avibration motor with a single eccentric weight when they have the samesize and the same number of motor rotation. In addition, it was alsoconfirmed that a vibration motor unit tilted with the eccentric weight10 b end down also has vibration increased in the direction Z.

In the above embodiment, the vibration motor body has a cylindricalmotor frame. However, the motor frame may be rectangular. The horizontalpositions, heights, and the tilting angle of the wing-like legs providedto the holder may be determined from the viewpoint of design.

In the above embodiment, the wing-like legs of the holder is used totilt the vibration motor body. However, a tilting means may be providedon the circuit board. In other words, the means for tilting thevibration motor in relation to the circuit board is not restricted tothe wing-like legs of the holder.

1. A vibration motor holding structure comprising: a holder, for holdinga vibration motor with at least one eccentric weight at either end of arotation shaft of the vibration motor, wherein said holder beingconfigured to hold an outer peripheral surface of a motor barrelelastically while contacting with a top face of the motor, the motorbarrel having a first lateral side and a second lateral side, a firstpart of the holding portion contacting and holding the outer peripheralsurface on the first lateral side of the motor barrel, the first part ofthe holding portion extending onto the second lateral side of the motorbarrel and contacting a bottom portion of the motor barrel to supportthe motor barrel, and a distal edge of the first part of the holdingportion closely opposes to a distal edge of a second part of the holdingportion, the second part of the holding portion contacting and holdingthe outer peripheral surface on the second lateral side of the motorbarrel.
 2. The vibration motor holding structure according to claim 1,wherein said holder has at least one set of wing-like legs on eitherlateral side of the motor barrel, said wing-like legs extend radiallyoutward of the motor barrel and in parallel with an axis of the motorbarrel.
 3. The vibration motor holding structure according to claim 2,wherein said wing-like legs are fixed to a circuit board at side edgesof a cutout of the circuit board to hold said vibration motor on saidcircuit board by soldering.
 4. A vibration motor holding structureaccording to claim 2, wherein said wing-like legs are fixed to a circuitboard at the side edges of a cutout of the circuit board to hold saidvibration motor on said circuit board by reflow soldering.
 5. Avibration motor holding structure according to claim 1, furthercomprising a tilting means for mounting said vibration motor on thecircuit board in a tilted manner in the longitudinal direction of themotor.
 6. A vibration motor held on a circuit board with the vibrationmotor holding structure according to claim
 1. 7. A vibration motor foruse in a portable communication device or a game machine held on acircuit board with the vibration motor holding structure according toclaim
 1. 8. A vibration motor held on a circuit board with the vibrationmotor holding structure according to claim 1, wherein a tilting meansfor mounting the vibration motor on the circuit board in a tilted mannerwith respect to the longitudinal direction of the motor is provided onthe vibration motor holding structure.
 9. A vibration motor holdingstructure according to claim 1, wherein said vibration motor haseccentric weights at both ends of said rotation shaft.
 10. A vibrationmotor holding structure comprising: a holder, for holding a vibrationmotor with at least one eccentric weight at either end of a rotationshaft of the vibration motor, the vibration motor having a motor barrelwith a first lateral side, a second lateral side, and a bottom disposedbetween the first lateral side and the second lateral side, the holderhaving a first part and a second part, the first part extending from thefirst lateral side of the motor barrel onto the second lateral side ofthe motor barrel and contacting a top face of the motor barrel and thebottom of the motor barrel to support the motor barrel, the second partof the holder contacting and holding the outer peripheral surface of themotor barrel on the second lateral side of the motor barrel.
 11. Thevibration motor holding structure of claim 10, wherein the holder has atleast one set of wing-like legs on either lateral side of the motorbarrel, the wing-like legs extending radially outward of the motorbarrel and in parallel with an axis of the motor barrel.
 12. Thevibration motor holding structure of claim 10, wherein a distal end ofthe first part of the holder is proximate a distal end of the secondpart of the holder.
 13. The vibration motor holding structure of claim10, further comprising a tilting means for mounting said vibration motoron the circuit board in a tilted manner in the longitudinal direction ofthe motor.
 14. A vibration motor holding structure according to claim10, wherein said vibration motor has eccentric weights at both ends ofsaid rotation shaft.
 15. A vibration motor holding structure for holdinga vibration motor having at least one eccentric weight at either end ofa rotation shaft of the vibration motor, the vibration motor also havinga motor barrel with a first lateral side, a second lateral sidegenerally opposite the first lateral side, a bottom disposed between thefirst lateral side and the second lateral side, and a top side disposedbetween the first lateral side and the second lateral side and generallyopposite the bottom, the holding structure comprising: a first supportextending about a periphery of the motor barrel from the first lateralside of the motor barrel to the second lateral side of the motor barreland contacting the bottom of the motor barrel to support the motorbarrel; and a second support extending about a periphery of the of themotor barrel on the second lateral side of the motor barrel; and whereinat least one of the first support and the second support having at leastone set of wing-like legs extending radially outward of the motor barreland in parallel with an axis of the motor barrel.
 16. The vibrationmotor holding structure of claim 15, wherein a distal end of the firstsupport is disposed proximate a distal end of the second support. 17.The vibration motor holding structure of claim 16, wherein the distalend of the first support and the distal end of the second support aredisposed on the second lateral side of the motor barrel.